Preparation of cis-diamminediaquaplatinum(II) nitrate

Abstract

A process is provided for preparing cis-[Pt(NH2)3(H2O)2](NO3)2 by a process comprising preparing cis-Pt(NH3)2I2 from K2PtI4 under controlled conditions of temperature and pH and converting the resultant cis-Pt(NH3)2I2 to the diaqua complex with AgNO3 under controlled conditions.

What is claimed is: 
     
       1. A process for preparing a cis-diamminediiodoplatinum(II) complex of high purity and in high yield from potassium tetraiodoplatinum(II) by a method comprising adding an aqueous solution of ammonium hydroxide to an aqueous dispersion of potassium tetraiodoplatinum(II), said tetraiodo compound having the formula K 2  PtI 4 , under a controlled gradually rising temperature profile while controlling the ammonium hydroxide addition so that the pH does not exceed about 7.5, washing and drying the resultant precipitated cis-Pt(NH 3 ) 2  I 2 , slowly adding the washed and dried cis-Pt(NH 3 ) 2  I 2  to an aqueous solution of AgNO 3  at room temperature and with rapid stirring, warming the silver-containing mixture to a maximum temperature of about 50° C. and maintaining the temperature of about 50° C. for a period of time sufficient substantially to complete the reaction, then cooling the resultant silver-containing reaction mixture to room temperature to form a solution containing cis-[Pt(NH 3 ) 2  (H 2  O) 2  ](NO 3 ) 2  and a AgI precipitate and separating the precipitated AgI from the solution containing cis-[Pt(NH 3 ) 2  (H 2  O) 2  ](NO 3 ) 2 . 
     
     
       2. A process according to claim 1, wherein the AgNO 3  reagent is used in an amount slightly below stoichiometric for complete conversion of cis-Pt(NH 3 ) 2  I 2 , and after separation of the AgI, to the remaining solution is added MCl (where M=K or Na) in a small but effective amount for precipitating Ag + , and precipitated AgCl is separated from the solution, thereby forming a purified solution of cis-[Pt(NH 3 ) 2  (H 2  O) 2  ](NO 3 ) 2  with minimized Ag +  content. 
     
     
       3. A process according to claim 1, wherein the Ag +   in solution containing cis-[Pt(NH 3 ) 2  (H 2  O) 2  ](NO 3 ) 2  is monitored with a silver/silver chloride electrode to minimize the Ag +  in solution. 
     
     
       4. A process for preparing cis-[Pt(NH 3 ) 2  (H 2  O) 2  ](NO 3 ) 2  of high purity and in high yield comprising: slowly adding a concentrated aqueous solution of KCl to a solution of chloroplatinic acid at a temperature of about 50° to about 60° C., to precipitate K 2  PtCl 6 , cooling the solution to about 0° C. and permitting it to stand to ensure complete precipitation, separating and washing the K 2  PtCl 6  precipitate, adding dropwise and at room temperature to an aqueous dispersion of the washed K 2  PtCl 6  an aqueous solution of N 2  H 4 .2HCl in excess of the stoichiometric amount, warming the resultant mixture to about 60° C. until the dispersed K 2  PtCl 6  has dissolved, thereafter heating the solution stepwise up to about 85° C. thereby forming K 2  PtCl 4  in solution, adding an aqueous solution of KI to the aqueous solution of K 2  PtCl 4  to convert said K 2  PtCl 4  to the corresponding K 2  PtCl 4  at a temperature of about 40° C. and maintaining the solution at a temperature to about 40° C. to about 85° C. to maximize conversion to K 2  PtI 4  to a water dispersion of said K 2  PtI 4 , at a temperature of about 40° C. adding a dilute solution of NH 4  OH slowly with stirring and with pH control so that the pH of 7.5 is not exceeded during the addition until the K 2  PtI 4  dispersion dissolves, maintaining the resultant solution at a temperature of about 40° C. to about 60° C. and adding additional NH 4  OH to a pH of about 7.5, then cooling the pH-adjusted solution to room temperature to precipitate cis-Pt(NH 3 ) 2  I 2 , separating and washing the precipitated cis-Pt(NH 3 ) 2  I 2 , adding the washed cis-Pt(NH 3 ) 2  I 2  to an aqueous solution of AgNO 3  while stirring and at room temperature, said AgNO 3  being present in a controlled amount to react with the cis-Pt(NH 3 ) 2  I 2  with minimum unreacted Ag, warming the silver-containing mixture to about 50° C. to ensure complete reaction and then cooling the resultant silver-containing mixture thereby forming a AgI precipitate and an aqueous solution containing cis-[Pt(NH 3 ) 2  (H 2  O) 2  ](NO 3 ) 2 .